The grasshopper "invasion" many Las Vegas residents are seeing is so rampant that swarms of the insects are showing up on weather radar. Some of the areas on the radar that would normally indicate a steady rainfall in fact represent masses of grasshoppers. The National Weather Service operating out of Las Vegas posted on Twitter, "Radar analysis suggests most of these echoes are biological targets. This typically includes birds, bats, and bugs, and most likely in our case--> Grasshoppers." State entomologist Jeff Knight says that such an invasion is not abnormal after such high rainfall totals. "There are some special weather conditions that trigger the migration," he says.